Problem

At Meta scale, hosts in data centers and corporate networks must obtain IP configuration reliably and securely before they can reach internal services. Explain how DHCP works end to end, and discuss the operational and security implications a DevOps engineer should understand when supporting Meta infrastructure.

Requirements

Your answer should cover:

1. Core flow: Describe the standard DHCP lease process from a new client joining the network through address assignment and renewal.
2. Protocol details: Name the main message types involved and what information is exchanged in each step.
3. Network behavior: Explain how DHCP works when the server is on a different subnet, including the role of relay agents.
4. Lease lifecycle: Describe lease time, renewal, rebinding, and what happens when a lease expires.
5. Security risks: Identify common attack or failure scenarios such as rogue DHCP servers, starvation attacks, spoofing, or misconfiguration.
6. Mitigations: Propose practical controls a Meta DevOps engineer could use to harden DHCP-dependent environments.

Example Prompt Framing

Assume a new server in a Meta rack boots via PXE, fails to reach internal services, and network logs show repeated DHCP discovery traffic. Walk through what should happen, where the failure may be occurring, and what signals you would inspect first.

What a strong answer includes

A strong answer clearly explains the DORA sequence (Discover, Offer, Request, Acknowledge), distinguishes broadcast vs unicast behavior, mentions UDP ports 67/68, explains relay behavior across VLANs/subnets, and connects DHCP mechanics to security controls such as DHCP snooping, port security, network segmentation, and monitoring for anomalous lease activity.